Masticatory mechanics of a mandibular distraction osteogenesis site: interfragmentary micromovement

Micromovement at a fracture or distraction osteogenesis (DO) site may play a significant role in bone formation and healing. Mastication is an important physiological process that can cause substantial micromovement at a mandibular disjunction. The purpose of this study is to characterize and quantify the micromovement caused by mastication. Eighteen pigs, divided into three groups based on duration of consolidation, received a unilateral (right) mandibular angle distraction osteogenesis protocol. Differential variable reluctance transducers (DVRTs) and ultrasound crystals were used to measure the change of gap width as well as interfragmentary movement during mastication. Synchronized chewing video and interfragmentary movement recordings were used to determine the magnitude and direction of micromovement at different phases of the chewing cycle. The magnitude of micromovement did not increase significantly with distraction up to almost 5 mm, but did decrease gradually with consolidation. The average micromovement magnitude during the distraction phase was 0.2-0.3 mm, equaling 50,000-250,000 microstrain (muepsilon) on interfragmentary tissue. The dominant deformation pattern was bending in the sagittal plane. The most common direction of bending at the power stroke of chewing was concave dorsally, i.e., superior shortening and inferior lengthening. These findings elucidate how masticatory mechanics affect a mandibular distraction site, and the measurements may be useful for future simulation studies.     

Treatment of cubitus varus using the Ilizarov technique of distraction osteogenesis

Seven children with a post-traumatic cubitus varus deformity were treated using the Ilizarov technique of distraction osteogenesis. The outcome was rated as excellent in each case and all were satisfied with the cosmetic appearance. No complications had been encountered by the latest follow-up at a mean of 66.7 months. This technique seems reliable for the treatment of such deformities, provided that it achieves full correction by gradual distraction. Nerve palsy and unsightly scars are avoided, and the range of movement of adjacent joints is preserved.     

Distraction osteogenesis by Ilizarov and unilateral external fixators in a canine model

We studied distraction osteogenesis in canine experimental model using two types of external fixators, Ilizarov (n=6) or AO unilateral (n=9) external fixator. Distraction started 1 week after surgery (2 x 0.5 mm/day) and lasted for 3 weeks. Specimens were harvested from weeks 7 through 12. The outcome was assessed by X-ray, histology, histomorphometry and microradiography. Bone regeneration as observed by X-rays was satisfactory and similar in both groups. Both endochondral ossification and intramembranous ossification were found simultaneously in both groups. In both groups, bone formation parameters were significantly higher in the area of consolidating bone. No differences in histomorphometric parameters existed between the groups. In the study period, the bone formation was enhanced and prevailed in the distraction area. This study demonstrated the utility of the canine experimental model for the study of distraction osteogenesis.     

Direct and indirect loading of the Ilizarov external fixator: the effect on the interfragmentary movements and compressive loads

The amount of weight bearing and the force transmission to the frame have an important influence on the results of treatment with an Ilizarov external fixator. The frame provides beneficial interfragmentary movements and compressive loads at the fracture site through elastic wires. Mobilisation can be achieved by applying a weight-bearing platform at the distal end of the fixator. The effect on the interfragmentary movements and the compressive loads in indirect and direct loading were analysed in this study using a composite tibia bone model. Displacement transducers were attached to measure the interfragmentary movements and to detect relative movements of the bone fragments and movements between the rings. The compressive loads in the osteotomy were measured with loading cells in the defect zone. The weight-bearing platform had a substantial effect on the biomechanical behaviour of the frame. It led to an indirect force transmission through the fixator with respect to the osteotomy, resulting in lower compressive loads, lower interfragmentary movements and higher mechanical stress on the frame.     

Influence of bone staple design on interfragmentary compression.

Staple fixation, most commonly thought of as static, has been studied with regard to effecting dynamic compression. Features of staple design that relate to the creation of interfragmentary compression have been analyzed, and a simple manipulative technique to effect compression is illustrated. Compressive forces of bone fixation staples were measured using pressure-sensitive film. Thirteen staple designs were tested in a wood-block model and in cadaveric bone. Staples with legs splayed outward produced higher compressive forces than standard staple designs. Internal beveling of the staple leg tips also produced high compressive forces, while external beveling produced distraction. Staples with legs tapered over their entire length produced compression, but caused splitting in the wood-block model. Our results show that outward splaying of the staple legs is a simple method to increase compression in any staple design.     

Results of using Ilizarov distraction osteogenesis technique for the treatment of cubitus varus deformities in adults

Introduction  

Five adult patients, with posttraumatic cubitus varus deformity underwent corrective surgery by the Ilizarov method of distraction osteogenesis.     

Limb lengthening in children and osteogenesis using the technics of Wagner and Ilizarov and their modifications

Different methods of lower limb lengthening are reviewed, related to delays in strengthening and type of callus: Wagner's technique (5 cases), decortication 3 weeks before osteotomy (1 case), and Ilizarov's technique (10 cases on 8 tibiae and 6 femurs). In 5 cases, decortication with osteotomy-closure and waiting 2 weeks before beginning lengthening, was performed. This was carried out at 1 mm/day. The type of fixator is unimportant. This technique allows a restitution of the tubular bone structure in 3 or 4 months in a periosteo-cortico-medullary callus.     

A biomechanical comparison of micromotion after ankle fusion using 2 fixation techniques: intramedullary arthrodesis nail or Ilizarov external fixator

BACKGROUND: In difficult ankle arthrodesis situations, intramedullary (IM) arthrodesis nails and external fixation are often considered in lieu of standard fusion techniques. The purpose of this study was to compare the amount of micromotion measured across an ankle fusion site stabilized with either an IM nail or with the Ilizarov external fixator. MATERIALS AND METHODS: The relative bone mineral density of 8 pairs of human cadaveric lower legs was measured by DEXA scanning. One specimen from each pair was randomly assigned to be stabilized with a new generation IM nail and the other with an Ilizarov external fixator. Specimens were tested in compression, rotation, and dorsiflexion. Optical motion capture was used to measure the direct motion occurring at the fusion site. RESULTS: No significant difference was found between the axial displacements (p = 0.94), torsional displacement (p = 0.07), or the dorsiflexion angular displacement (p = 0.28) for the IM rod group and the external fixation group. A weak correlation was found between BMD and displacement. CONCLUSION: Both the new generation IM nail and the Ilizarov external fixator imparted excellent stability to the fusion site despite a wide range of bone mineral densities. Medialization of the talus, the ability to compress the nail, and the addition of a posterior-to-anterior locking screw were thought to improve the performance of the nail. CLINICAL RELEVANCE: Both IM nail and Ilizarov external fixation provided excellent fusion site stability. The decision of which implant to use for complex arthrodesis should be dictated by the clinical needs.     

Modified Ilizarov technique for infected nonunion of the femur: the principle of distraction-compression osteogenesis

PURPOSE. To evaluate the treatment outcome of the modified Ilizarov technique in infected nonunion of the femur. METHODS. Between 1989 and 2002, records of 20 patients with infected nonunion of the femur treated with the modified Ilizarov technique were retrospectively reviewed. The modified Ilizarov frame was fixed after necrectomy of the dead infected bone and tissues. A proximal or distal corticotomy was performed following biological principles. For regeneration of gap, segmental transport was performed in 11 patients with a gap of more than 5 cm; acute docking followed by lengthening at the corticotomy site was performed in 9 patients with a gap of smaller than 5 cm. Mobilisation was started early with active participation of the physical therapist and the patients. Bone and functional results were measured and complications were categorised according to the Association for the Study and Application of the Method of Ilizarov guidelines. RESULTS. The mean follow-up period was 62.8 months. Bony union and eradication of the infection was achieved in all patients except one who underwent amputation due to uncontrolled infection. Bone results were excellent in 13 patients, good in 4, fair in one, poor in one, and treatment failure (amputation) in one. Functional results were excellent in 3 patients, good in 9, fair in 3, poor in 4, and failure in one. A total of 71 complications occurred: 35 problems, 6 obstacles, and 30 true complications. The mean healing index was 38.3 day/cm (standard deviation, 1.6 day/cm). CONCLUSION. The Ilizarov technique is a good salvage operation for infected nonunion of the femur. Limb salvage is preferable to prosthesis if the limb is viable, adequately innervated and the patient is mentally and financially committed to save the limb.     

Ilizarov distraction osteogenesis over the preexisting nail for treatment of nonunited femurs with significant shortening

Purpose

Nonunion of the femur with significant shortening with retained intramedullary nail (IMN) is a challenging orthopedic problem. We investigated whether the application of Ilizarov distraction osteogenesis over the preexisting nail can simultaneously achieve union and correct shortening.

Methods

Thirteen patients with femoral diaphyseal nonunion associated with significant shortening with retained IMN were retrospectively reviewed. All patients were treated by distraction osteogenesis using a circular external fixator over the preexisting nail. The fixator was used to compress or distract the nonunion site and to gradually distract a separate osteotomy to restore limb length. The osteotomy was done percutaneously using the Gigli saw with the nail in situ. The applied surgical technique was bifocal compression distraction in 11 cases, bifocal distraction in one case, and monofocal distraction in one case.

Results

Bone healing was achieved in 11 cases (84.6 %) at both the nonunion and the lengthening sites. The mean length gained was 4 cm (range, 3–6 cm). The mean time to fracture union was 4.9 months (range, 4–6 months). The mean knee flexion improved from 86.5° (range, 40°–135°) preoperatively to 109.6° (range, 60°–125°) at final follow-up (p < 0.05). The mean limb-length discrepancy improved from 4.7 cm (range, 3–7.5) preoperatively to 0.7 cm (range, 0–3) at final follow-up (p < 0.001). Ten out of 13 patients had a total of 14 complications, with a mean of 1.1 complications per patient.

Conclusions

Distraction osteogenesis over the preexisting nail can be a good alternative to treat difficult femoral diaphyseal nonunions associated with significant shortening.

     

Ilizarov ankle arthrodesis.

Six consecutive patients, four with failed infected ankle fusions and two with posttraumatic degenerative ankle arthritis, were treated by monofocal compression arthrodesis using the Ilizarov external fixator. The average age was 48 years (range, 33-74 years). The average preoperative duration after failed infected ankle fusion was 18 months and for posttraumatic arthritis after fracture, 23 months. Infected failed pseudarthroses had significant fixed valgus deformity of the foot, bilateral draining sinuses, and near complete destruction and loss of the talus. Compression was dynamically applied during treatment. Custom foot plates were secured to the frame, and weight bearing as tolerated was allowed throughout the treatment period. Tibiocalcaneal fusion was obtained in three of four infected failed ankle fusions at an average of seven months (range, five to nine months). There was no evidence of infection at follow-up evaluation in these patients. One patient did not tolerate the frame and developed a fibroarthrosis. One patient sustained a refracture of the fusion at six months. Successful tibiocalcaneal fusion was obtained with reapplication of the frame and a Pappineau graft. Two primary ankle fusions healed with tibial talar fusion at an average of 3.5 months. Overall follow-up time averaged 26 months (range, 19-30 months). Six wires broke, requiring simple replacement. Four of these six were 1.5-mm wires. The Ilizarov frame may have several advantages in primary ankle arthrodesis and in the salvage of infected failed ankle fusions.     

Biomechanical studies of forces occurring in the Ilizarov and Orthofix apparatuses during limb lengthening by distractive osteogenesis]

The magnitude of the distractive forces occurring in the Ilizarov and Orthofix apparatuses during limb lengthening by distractive osteogenesis has been investigated. Eighteen patients treated between 1995 and 1998 were included in the study. The data obtained were computerized and related to clinical, radiographic and sonographic findings. Typical and repeatable graphs of forces were found during the process of lengthening as well as typical relationships between the callus and the values of distractive forces.     

Osteomyelitis. The Ilizarov perspective.

It is evident that Professor Ilizarov has devised some remarkable strategies for dealing with chronic osteomyelitis. In summary, his methods include: Extensive debridement and intercalary bone transport. Oblique osteotomy through multiloculated cavitary osteomyelitis in intact bone. Elimination of large cavities by gradual displacement of one cortical wall. The role that these techniques will play in the future of osteomyelitis surgery remains to be determined by careful clinical and experimental research.     

Intermittent micromotion inhibits bone ingrowth. Titanium implants in rabbits.

We studied the effects of micromotion on bone ingrowth into a 1-mm canal through a titanium chamber implanted in the proximal tibia of rabbits. The implant surface became "osseointegrated," but an interior core was movable, allowing the central portion of the canal to be moved in relation to the ends. Thus, the ingrowing bone in the canal had to pass an area of ad latus motion. When implanted in rabbit tibiae, the canal became filled with ingrown cancellous bone. Bone ingrowth was inhibited by 20 cycles of 0.5-mm movement applied during a 30-second period once daily. With this regimen, the canal was usually filled with vascularized fibrous tissue and significantly less bone. The micromotion chamber may enable detailed studies of the effects of different motion variables on ingrowth of bone.     

伊里扎诺夫技术修复兔胫骨骨缺损成骨机制的研究

目的探讨截骨推移区骨愈合的组织学特点和新骨形成规律。方法取青紫蓝兔24只,建立胫骨大段骨缺损模型,在近干骺端截骨。分别于截骨后第1、2、4、6、8、10周各处死4只兔,在近干骺端的分离区取材进行组织学观察。结果截骨后第1周出现血肿机化,第4周出现膜内成骨和软骨内成骨,第6周推移区大部分被骨性骨痂取代,第8周开始改建。结论推移区存在膜内成骨和软骨内成骨2种方式,以膜内成骨为主。     

The Bone Tie. A new device for interfragmentary fixation

A new method of bone fixation is described, using a small stainless steel device to provide compression between fragments with a single drill hole. The Bone Tie uses an old architectural principle to hold bone fragments together with minimal surgical dissection for access. The technique has been used in 14 cases, and the results are presented. In ten cases the outcome was good. Complications were encountered in four, mostly through technical error, although the final outcomes were acceptable.     

Tibial fractures. The Ilizarov alternative.

Between February 1988 and May 1989, 17 consecutive patients with 18 tibial fractures were treated using the Ilizarov method and apparatus. Injuries included four closed fractures and 14 open fractures. There were three Grade I open, four Grade II open, and seven Grade III open tibial fractures. Indications for application of the Ilizarov frame included fractures that were determined to need surgical management primarily, or fractures that had failed to heal by other treatment methods, either operative or nonoperative. Patients averaged 17.7 months of follow-up treatment. One patient was lost to follow-up treatment after the fracture healed and the device was removed. To date, all fractures are healed. There was one delayed union, which subsequently healed with a second application of the device. Complications included two late wound infections, both in Grade III open fractures. These occurred after removal of the Ilizarov apparatus. The average time from application of the device to complete fracture healing was 5.6 months, with a range of 3.25 to 13 months. This compares favorably with the results described for other treatment modalities. These results indicate that the Ilizarov method is indeed a useful adjunct in the orthopedic armamentarium for the treatment of either open or closed tibial fractures. No practical contraindications to the use of the Ilizarov device in the management of tibial fractures were encountered.     

Ilizarov technique. Results and difficulties.

Of 100 cases treated by the Ilizarov method, 91 patients were reviewed from February 1985 to March 1990. There were 32 tibial fractures (29 open) and 21 nonunions (nine infected). There were 47 cases of limb lengthening (28 tibia and 19 femur). The results were as follows: good, 83%; fair, 13%; and poor, 4%. Slight and intermittent pain in some wire of the device was frequent (69%). Average bone healing time in tibial fractures was 4.95 months and 5.83 months in tibial nonunions. In bone-lengthening operations, the average lengthening index in the tibia was 1.02 months/cm (lengthenings ranged from 3 cm to 10 cm, with a mean of 5.71 cm), whereas in the femur, the average lengthening index was 1.14 months/cm (lengthenings ranged from 3 cm to 7 cm, with a mean of 5.34 cm). Manually-tensed wires produced frequent problems (24.5%), whereas wire tensed by the dynamometric tensioner produced problems in only 7.8% of the cases. Despite good results, the Ilizarov technique requires adequate training to reduce an overall complication rate (approximately 30%).